Barbora Vitverova

High Levels of Soluble Endoglin Induce a Proinflammatory and Oxidative-Stress Phenotype Associated with Preserved NO-Dependent Vasodilatation in Aortas from Mice Fed a High-Fat Diet

Aims: A soluble form of endoglin (sEng) was proposed to participate in the induction of endothelial dysfunction in small blood vessels. Here, we tested the hypothesis that high levels of sEng combined with a high-fat diet induce endothelial dysfunction in an atherosclerosis-prone aorta. Methods and Results: Six-month-old female and male transgenic mice overexpressing human sEng (Sol-Eng+) with low (Sol-Eng+low) or high (Sol-Eng+high) levels of plasma sEng were fed a high-fat rodent diet containing 1.25% cholesterol and 40% fat for 3 months. The plasma cholesterol and mouse sEng levels did not differ in the Sol-Eng+high and Sol-Eng+low mice. The expression of proinflammatory (P-selectin, ICAM-1, pNFκB and COX-2) and oxidative-stress-related markers (HO-1, NOX-1 and NOX-2) in the aortas of Sol-Eng+high female mice was significantly higher than in Sol-Eng+low female mice. Endothelium-dependent vasodilatation induced by acetylcholine was preserved better in the Sol-Eng+ high female mice than in the Sol-Eng+low female mice. Conclusion: These results suggest that high concentrations of sEng in plasma in combination with a high-fat diet induce the simultaneous activation of proinflammatory, pro-oxidative and vasoprotective mechanisms in mice aorta and the balance of these biological processes determines whether the final endothelial phenotype is adaptive or maladaptive.

Soluble endoglin modulates the pro-inflammatory mediators NF-κB and IL-6 in cultured human endothelial cells

Aims: Endoglin is a transmembrane glycoprotein, that plays an important role in regulating endothelium. Proteolytic cleavage of membrane endoglin releases soluble endoglin (sEng), whose increased plasma levels have been detected in diseases related to the cardiovascular system. It was proposed that sEng might damage vascular endothelium, but detailed information about the potential mechanisms involved is not available. Thus, we hypothesized that sEng contributes to endothelial dysfunction, leading to a pro‐inflammatory phenotype by a possible modulation of the TGF‐&bgr; and/or inflammatory pathways. Main methods: Human umbilical vein endothelial cells (HUVECs) and Human embryonic kidney cell line (HEK293T) were treated with different sEng concentration and time in order to reveal possible effect on biomarkers of inflammation and TGF‐&bgr; signaling. IL6 and NF&kgr;B reporter luciferase assays, quantitative real‐time PCR analysis, Western blot analysis and immunofluorescence flow cytometry were used. Key findings: sEng treatment results in activation of NF‐&kgr;B/IL‐6 expression, increased expression of membrane endoglin and reduced expression of Id‐1. On the other hand, no significant effects on other markers of endothelial dysfunction and inflammation, including eNOS, peNOSS1177, VCAM‐1, COX‐1, COX‐2 and ICAM‐1 were detected. Significance: As a conclusion, sEng treatment resulted in an activation of NF‐&kgr;B, IL‐6, suggesting activation of pro‐inflammatory phenotype in endothelial cells. The precise mechanism of this activation and its consequence remains to be elucidated. A combined treatment of sEng with other cardiovascular risk factors will be necessary in order to reveal whether sEng is not only a biomarker of cardiovascular diseases, but also a protagonist of endothelial dysfunction.

Soluble endoglin and hypercholesterolemia aggravate endothelial and vessel wall dysfunction in mouse aorta

BACKGROUND AND AIMS Increased plasma levels of soluble endoglin (sEng) were detected in patients with endothelial dysfunction-related disorders and hypercholesterolemia. In this study, we hypothesized that high levels of sEng accompanied by mild hypercholesterolemia could aggravate endothelial and vessel wall dysfunction and affect endoglin/eNOS signaling in mouse aorta. METHODS Three-month-old female transgenic mice on CBAxC57BL/6J background, with high levels of sEng (Sol-Eng+high HFD), and their littermates with low levels of sEng (Sol-Eng+low HFD), were fed a high fat diet for six months. Plasma samples were used for biochemical, ELISA and Luminex analyses of total cholesterol, sEng and inflammatory markers. Functional parameters of aorta were assessed with wire myograph 620M. Western blot analyses of membrane endoglin/eNOS signaling and endothelial dysfunction/inflammation markers in aorta were performed. RESULTS Functional analysis of aorta showed impaired KCl induced vasoconstriction, endothelial-dependent relaxation after the administration of acetylcholine as well as endothelial-independent relaxation induced by sodium nitroprusside in the Sol-Eng+high HFD group compared to the Sol-Eng+low HFD group. Ach-induced vasodilation after administration of l-NAME was significantly higher in the Sol-Eng+high HFD group compared to the Sol-Eng+low HFD group. The expression of endoglin, p-eNOS/eNOS, pSmad2/3/Smad2/3 signaling pathway was significantly lower in the Sol-Eng+high HFD group compared to the Sol-Eng+low HFD group. CONCLUSIONS The results indicate that long-term hypercholesterolemia combined with high levels of sEng leads to the aggravation of endothelial and vessel wall dysfunction in aorta, with possible alterations of the membrane endoglin/eNOS signaling, suggesting that high levels of soluble endoglin might be considered as a risk factor of cardiovascular diseases.